1. Field of the Invention
This invention relates to guide shoes for oil well development and particularly to a self-orienting guide shoe for oil well development
2. Description of the Prior Art
The process of drilling for oil is a multi-step process. First, a borehole is drilled into the ground using a drill bit and drill motor attached to the bottom of the drill string. Drilling mud lubricates the borehole and provides the means to power the drill motor. After the borehole has been drilled to a sufficient depth, tubing is inserted into the borehole. Extended reach wells requires a significant axial force to be placed upon the tubing string during the insertion process. Once the tubing reaches final depth, the bore hole and tubing are cleaned and clearance between the tubing and bore hole is provided by pumping high pressure fluid into the tubing string and then out through a guide shoe, which forces debris upward and out of the hole. This is followed by high pressure pumping of cement to secure the tubing into the ground and for zonal isolation. The guide shoe is attached to the bottom of the tubing string and is used to negotiate well bores that have a high degree of deviation, ledges, and depths inherent in extended reach directional drilling. Advanced technology utilized in current guide shoe design includes a rotating eccentric nose that can better negotiate well deviations, and a means of centralization to reduce affects of friction to achieve greater total depth. A problem with the prior art devices is that they do not address the need to overcome friction of the guide shoe and the well bore to orient the eccentric nose to an advantageous position that would enable to the guide shoe to negotiate extreme deviations and ledges in the hole. Rotating guide shoes have the problem of slipping on obstacles, which make progress inefficient, if not impossible. Some guide shoes use reamers to cut through the obstructions without rotating, this is better than simply spinning in place, but can cause difficulties, depending on the material contacted.